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// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package netstack wires up gVisor's netstack into Tailscale.
package netstack
import (
"context"
"fmt"
"log"
"net"
"strings"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/link/channel"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
"gvisor.dev/gvisor/pkg/waiter"
"inet.af/netaddr"
"tailscale.com/types/logger"
"tailscale.com/wgengine"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/magicsock"
"tailscale.com/wgengine/packet"
"tailscale.com/wgengine/tstun"
)
func Impl(logf logger.Logf, tundev *tstun.TUN, e wgengine.Engine, mc *magicsock.Conn) error {
ipstack := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocol{ipv4.NewProtocol()},
TransportProtocols: []stack.TransportProtocol{tcp.NewProtocol(), udp.NewProtocol(), icmp.NewProtocol4()},
})
const mtu = 1500
linkEP := channel.New(512, mtu, "")
const nicID = 1
if err := ipstack.CreateNIC(nicID, linkEP); err != nil {
log.Fatal(err)
}
ipstack.AddAddress(nicID, ipv4.ProtocolNumber, tcpip.Address(net.ParseIP("100.96.188.101").To4()))
// Add 0.0.0.0/0 default route.
subnet, _ := tcpip.NewSubnet(tcpip.Address(strings.Repeat("\x00", 4)), tcpip.AddressMask(strings.Repeat("\x00", 4)))
ipstack.SetRouteTable([]tcpip.Route{
{
Destination: subnet,
NIC: nicID,
},
})
// use Forwarder to accept any connection from stack
fwd := tcp.NewForwarder(ipstack, 0, 16, func(r *tcp.ForwarderRequest) {
logf("XXX ForwarderRequest: %v", r)
var wq waiter.Queue
ep, err := r.CreateEndpoint(&wq)
if err != nil {
r.Complete(true)
return
}
r.Complete(false)
c := gonet.NewTCPConn(&wq, ep)
// TCP echo
go echo(c, e, mc)
})
ipstack.SetTransportProtocolHandler(tcp.ProtocolNumber, fwd.HandlePacket)
go func() {
for {
packetInfo, ok := linkEP.ReadContext(context.Background())
if !ok {
logf("XXX ReadContext-for-write = ok=false")
continue
}
pkt := packetInfo.Pkt
hdrNetwork := pkt.NetworkHeader()
hdrTransport := pkt.TransportHeader()
full := make([]byte, 0, pkt.Size())
full = append(full, hdrNetwork.View()...)
full = append(full, hdrTransport.View()...)
full = append(full, pkt.Data.ToView()...)
logf("XXX packet Write out: % x", full)
if err := tundev.InjectOutbound(full); err != nil {
log.Printf("netstack inject outbound: %v", err)
return
}
}
}()
tundev.PostFilterIn = func(p *packet.ParsedPacket, t *tstun.TUN) filter.Response {
var pn tcpip.NetworkProtocolNumber
switch p.IPVersion {
case 4:
pn = header.IPv4ProtocolNumber
case 6:
pn = header.IPv6ProtocolNumber
}
logf("XXX packet in (from %v): % x", p.SrcIP, p.Buffer())
vv := buffer.View(append([]byte(nil), p.Buffer()...)).ToVectorisedView()
packetBuf := stack.NewPacketBuffer(stack.PacketBufferOptions{
Data: vv,
})
linkEP.InjectInbound(pn, packetBuf)
return filter.Accept
}
return nil
}
func echo(c *gonet.TCPConn, e wgengine.Engine, mc *magicsock.Conn) {
defer c.Close()
src, _ := netaddr.FromStdIP(c.RemoteAddr().(*net.TCPAddr).IP)
fmt.Fprintf(c, "Hello, %s! Thanks for connecting to me on port %v (Try other ports too!)\nEchoing...\n",
mc.WhoIs(src),
c.LocalAddr().(*net.TCPAddr).Port)
buf := make([]byte, 1500)
for {
n, err := c.Read(buf)
if err != nil {
log.Printf("Err: %v", err)
break
}
c.Write(buf[:n])
}
log.Print("Connection closed")
}
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